Radiation curable compositions comprising an isocyanate modified polyfunctional ester and a photoinitiator

ABSTRACT

A RADIATION-CURABLE COMPOSITION COMPRISES AT LEAST ONE ISOCYANTAE-MODIFIED POLYFUNCTIONAL ESTER HAVING A HYDROXYL VALUE OF ABOUT 15-70 AND AT LEAST ONE PHOTOINITIATOR.

United States Patent Qlfice Patented Sept. 18, 1973 US. Cl. 204-45923Claims ABSTRACT OF THE DISCLOSURE A radiation-curable compositioncomprises at least one isocyanate-modified polyfunctional ester havin ahydroxyl value of about -70 and at least one photoinitiator.

This application is a continuation-in-part of copending application Ser.No. 244,910, filed Apr. 17, 1972, now abandoned, which is acontinuation-in-part of application Ser. No. 850,633, filed Aug. 15,1969, now abandoned.

This invention relates to radiation-curable compositions. Morespecifically it relates to radiation-curable compositions having reducedWater-sensitivity and reduced toxicity.

The use of radiation-curable ethylenically unsaturated monomericmaterials in coating compositions, adhesives, printing inks, and thelike is known. It is also known that such monomeric materials areconverted into polymers by the action of radiation and that they willpolymerize at an improved rate When they are exposed to actinicradiation in the presence of a photoinitiator, as disclosed in, forexample, US. Pats. 3,551,235; 3,551,246; 3,551,311; and 3,558,387.

The use of some of these materials, however, is somewhat limited bytheir strong aflinity for water. When, for example, the compositionswere formulated into printing inks for lithography, they absorbedexcessive amounts of fountain solutions, resulting in emulsification,tinting, weak printing, and poor Water-ink control. When used asadhesives the bonding properties often were poor due to absorbedatmospheric moisture; in coatings for paper they lacked gloss andsmoothness and they cured at a slower rate than when in a dry condition.The reason for this water-sensitivity is not now fully understood, butit is believed to be due, at least in part, to the presence of hydroxylgroups.

It has now been found that the hydrophobicity of these compositions canbe regulated as desired by modifying with an isocyanate the basemonomeric material of the composition. As used hereinafter, unlessotherwise specified monomeric material means both monomers andprepolymers, .that is, dimers, trimers, and other oligomers and mixturesand copolymers thereof. The resulting isocyanate-modified material hasdecreased water-sensitivity without loss in radiation-suscepti bility oradverse effect on its other properties, e.g., gloss, printability,smoothness, adhesion, and so forth.

Inks and coatings made from the compositions of the present inventionare free of volatile solvents, hydro phobic, and upon exposure to asource of radiation dry almost instantaneously in air at ambienttemperature, thus eliminating the need for ovens and the need to work inan oxygen-free environment as well as avoiding air pollution, firehazards, odor, and so forth, that accompany the use of coating, ink, andadhesive systems based on volatile solvents. The inks have excellentworkability on offset printing presses. The inks and coatings formextremely hard and durable films on a wide variety of substrates, suchas, for example, newsprint; coated paper stock; irregular, e.g.,corrugated, board; metal, e.g., foils, meshes, cans, and bottle caps;woods; rubbers; polyesters, such as polyethylene terephthalate; glass;polyolefins, such as treated and untreated polyethylene andpolypropylene; cellulose acetate; fabrics such as cotton, silk, andrayon; and the like. They exhibit no color change in the applied filmwhen subjected to the required curing conditions, and they are resistantto flaking; smudging; salt spray; scufiing; rubbing; and thedeteriorating effects of such substances as alcohols, oils, and fats. Inaddition, the compositions of this invention withstand both heat andcold, making them useful, for example, in printing inks or coatings forcontainers that must be sterilized, e.g., up to about C. under pressure,and/or refrigerated, e.g., at less than about 20 C.

In addition, the toxicological properties of some radiation-curablecompounds can be improved by modifying them with isocyanates. Thereduction in the hydroxy functionality and the increase in the molecularweight of the products when certain polyethylenically unsaturated estersare modified with isocyanates substantially reduce the health hazardsfrequently encountered in the manufacture and use of the base monomericesters.

In general the compositions of this invention comprise (a) at least oneradiation-curable isocyanate-modified polyethylenically unsaturatedester having a controlled hydroxyl content and (b) at least onephotoinitiator along with, if desired, (c) at least one colorant. Alsowithin the scope of this invention are compositions which comprise (a)at least one isocyanate-modified polyethylenically unsaturated esterwith controlled hydroxyl content, (b) at least one unmodifiedpolyethylenically unsaturated ester with free hydroxyl groups which isdifferent from the starting ester of (a), and (c) at least onephotoinitiator with or Without (d) at least one colorant.

Suitable starting compounds for use in the compositions of thisinvention are polyfunctional ethylenically unsaturated monomers andprepolymers, e.g., dimers, trimers, and other oligomers, and mixturesand copolymers thereof having a finite free hydroxyl content. Asemployed herein, the term polyethylenically unsaturated refers tocompounds having two or more pendant ethylenic groups. The monomers orprepolymers may be generally described as the acrylic acid, methacrylicacid, itaconic acid, and the like, esters of aliphatic polyhydricalcohols, such as for example the diand polyacrylates, the diandpolyrnethacrylates, and the diand polyitaconates of alkylene glycols,alkoxylene glycols, alicyclic glycols, and higher poly'ols, such asethylene glycol, triethylene glycol, tetraethylene glycol,tetramethylene glycol, trimethylolethane, trimethylolpropane,pentaerythritol, dipentaerythritol, tripentaerythritol, and the like, ormixtures of these with each other or with their partially esterifiedanalogs, and their prepolyrners, said compound or mixture having freehydroxyl content.

Typical compounds include, but are not limited to trimethylolpropanetriacrylate, trimethylolethane triacrylate, trimethylolpropanetrimethacrylate, trimethylolethane trimethacrylate, tetramethyleneglycol dimethacrylate, ethylene glycol dimethacrylate, triethyleneglycol dimethacrylate, tetraethylene glycol diacrylate, tetraethyleneglycol dimethacrylate, pentaerythritoll diacrylate, pentaerythritoltriacrylate, pentaerythritol tetraacrylate, dipentaerythritoldiacrylate, dipentaerythritol triacrylate, dipentaerythritoltetraacrylate, dipentaerytritol pentaacrylate; dipentaerythritolhexacrylate, tripentaerythritol octoacrylate, pentaerythritoldimethacrylate, pentaerythritol trimethacrylate, dipentaerythritoldimethacrylate, dipentaerythritol tetramethacrylate, tripentaerythritoloctamethacrylate, pentaerythritol diitaconate, dipentaerythritoltrisitaconate, dipentaerythritol pentaitaconate, dipentaerythritolhexaitaconate, and the like, and the mixtures and prepolymers thereof,mixtures of dimers and trimers of tripentaerythritol octoacrylate,mixtures of dimers and trimers of dipentaerythritol hexacrylate, and thelike, and mixtures thereof, wherein a low but finite hydroxyl contentmust exist.

The successful use of these esters in, for example, lithographic inksdepends on the hydrophilic/hydrophobic balance of the molecule, i.e.,the solubility of the monomer in water and the solubility of water inthe monomer. In order to control the hydrophilicity of these monomersand prepolymers, the molecule is chemically modified with an isocyanate,producing a product which exhibits the desired hydrophilic/hydrophobicbalance. It is essential, therefore, that the starting esters have somefree hydroxyl groups in order to react with the NCO group of theisocyanates. Thus, for example, in preparing trimethylolpropanetrimethacrylate the esterification reaction is not carried tocompletion, leaving unreacted hydroxyl groups in the monomeric material.

The above-described esters may be obtained in any convenient manner,such as for example by the ester interchange method of interacting alower alkyl ester of the acid with the alcohol in the presence of asuitable catalyst or by the reaction of the alcohol with the :,[3-unsaturated acids or acyl chlorides in the presence of suitable acidscavengers.

The monomer, prepolymer, or mixture thereof is reacted with anisocyanate to yield a compound that has increased hydrophobic propertiesand thus improved water-resistance, gloss, bonding qualities,smoothness, and so forth, as well as lower toxicity. Theisocyanate-modified ester is conveniently prepared by reacting themonomeric ester with an isocyanate under controlled conditions. Ingeneral the reaction is carried out within the range of about 25 to 100C., and preferably at about 50 C.

While it is possible to convert all of the hydroxyl groups of thestarting ester to carbamate groups, for the applications for which theproducts of this invention are most appropriate, i.e., inks, coatingcompositions, adhesives, and the like, it is essential not to convertall of the hydroxyl groups, that is, to leave in the composition someisocyanate-modified ester having free hydroxyl content. The completeconsumption of hydroxyl groups causes an undesirable condition known inthe art of lithography as ink stripping, that is, the phenomenon whereinthe ink does not pick up enough water to print satisfactorily. Theisocyanate-modified ester products should have a hydroxyl number ofabout 15 to 70 and preferably about 25 to 60. Hydroxyl number is definedby ASTM specification D-2849-69 as the milligrams of potassium hydroxideequivalent to the hydroxyl content of one gram of the sample.

The amount of isocyanate that must be reacted with the ester to obtain aproduct having optimum properties varies with the selected monomericester, with the selected isocyanate, and with the properties that arerequired for the intended end use. For example, for a phenylisocyanate-modified pentaerythritol triacrylate to be used in alithographic ink the conversion is preferably not more than about 60percent of the hydroxyl content; this provides good lithographingproperties with good storage stability.

In addition, the ratio of the -NCO groups to the OH groups is important;this also varies with the specific monomer and isocyanate selected.When, for example, the ester is a pentaerythritol-3.S-acrylate, that is,a mixture of approximately 50 mole percent of the triacrylate and 50mole percent of the tetraacrylate, the ratio of the NCO groups to theoriginal OH groups is generally within the range of about 0.2 to 0.8,and preferably the 4 ratio is about 0.6, leaving about 0.4 of theoriginal -OH groups unreacted.

Any of a wide variety of suitable organic isocyanates may be used,including aliphatic, cycloaliphatic, heterocyclic, and aromatic monoandpolyisocyanates, and combinations of these. Examples include, but arenot limited to, 6-ethyldecyl isocyanate, octadecyl isocyanate, phenylisocyanate, chlorophenyl isocyanate, stearyl isocyanate, cyclohexylisocyanate, 6-phenyldecyl isocyanate, 6-cyclohexyldodecyl isocyanate,2,4-tolylene diisocyanate, 2,6- tolylene diisocyanate, 1,4-phenylenediisocyanate, hexamethylene diisocyanate, 1,4-naphthalene diisocyanate,1,5- naphthalene diisocyanate, 4,4 -diphenylmethane diisocyanate, p,p-diphenyl diisocyanate, butylene-1,4-diisocyanate, ethylenediisocyanate, trimethylene diisocyanate, tetramethylene 1,4diisocyanate, butylene-2,3-diisocyanate, cyclohexylene-1,2-diisocyanate,methylene-bis (4-phenylisocyanate), diphenyl 3,3 dimethyl-4,4diisocyanate, xylylene diisocyanate, cyclohexane-l,4-diisocyanate,l-methoxyphenyl2,4-dii socyanate, benzene-1,2,4-triisocyanate,polymethylene polyphenylisocyanate, toluene-2,4,6-triisocyanate,4,4-dimethyldiphenyl methane-2,2,5,5tetra isocyanate, and the like, andmixtures thereof.

The isocyanate reacts with the ethylenically unsaturated hydroxylmaterial to give the carbamate reaction product, thus reducing the freehydroxyl content of the starting ester and so reducing its watersensitivity and its toxicity. This increase in hydrophobicity has madethe products more suitable for use as lithographic inks, adhesives,coating compositions, etc., without loss in stability and with, in someinstances, increased speed of curing.

Suitable photoinitiators for the compositions of this invention include,but are not limited to, the following: acyloins; acyloin derivatives,such as benzoin methyl ether, benzoin ethyl ether, desyl bromide, desylchloride, desyl amine, and the like; ketones, such as benzophe none,acetophenone, ethyl methyl ketone, cyclopentanone, benzil, caprone,benzoyl cyclobutanone, dioctyl acetone, and the like; substitutedbenzophenones, such as N,N- dimethylamino benzophenone, Michlers Ketone,and halogenated acetoand henzophenones; polynuclear quinones, such asbenzoquinone and anthraquinone; substituted polynuclear quinones, suchas chloroanthraquinone, methylanthraquinone, octamethylanthraquinone,napthtoquinone, dichloronaphthoquinone, and so forth; halogenatedaliphatic, alicyclic, and aromatic hydrocarbons and their mixtures inwhich the halogen may be chlorine, bromine, fluorine, or iodine, such asfor example chlorinated rubbers such as the Parlons (Hercules Inc.),copolymers of vinyl chloride and vinyl isobutyl ether such as VinofiexMP-400 (BASF Colors and Chemicals, Inc.), chlorinated aliphatic Waxessuch as Chlorowax (Diamond Alkali, Inc.), perchloropentacyclodecane suchas Dechlorane+ (Hooker Chemical Co.), chlorinated paraffins such asChlorafin 40 (Hooker Chemical Co.) and Unichlor-70B (Neville ChemicalCo.), monoand polychlorobenzenes; monoand polybromobenzenes, monoandpolychloroxylenes, monoand polybromoxylenes, dichloromaleic anhydride,l-(chloro-Z-methyl) naphthalene, 2,4-dimethylbenzene sulfonyl chloride,l-bromo-3-(mphenoxyphenoxy) benzene, 2-bromoethyl methyl ether,chlorendic anhydride and its corresponding esters, chloromethylnaphthylchloride, ehloromethyl naphthalene, bromomethyl phenanthrene,diiodomethyl anthracene, hexachlorocyclopentadiene, hexachlorobenzene,and the like; and mixtures thereof.

The radiation-curable composition may also include, if desired, about0.1 to 2.0 percent, based on the weight of the total composition, of anaccelerating agent, such as the mercaptans and their derivatives, forexample, ethyl mercaptoacetate; amine oxides, such as bis(Z-hydroxyethyl) cocoamine oxide and bis(2-hydroxyethyl) octadecylamineoxide; cyclized unsaturated aromatic hydrocarbons, e.g., neohexene,cyclohexene, cyclooctene, and dlimonene; and the like; and mixturesthereof. The above described additives may further be used in varyingmixtures. The modified radiation-curable esters may be ad ditionallymodified if desired, by the addition of a prepolymer, such as a diallylphthalate prepolymer, and a chain transfer agent; a prepolymer and anunsaturated compound reactive with oxygen, e.g., an alkyd resin; aprepolymer and a further modifying substance, e.g., cetyl vinyl ether; aviscosity control agent together with a chain transfer agent, aprepolymer or other modifying resin; and mixtures thereof.

The ratio of the amount of the isocyanate-modified monomeric ester tothe photoinitiator in the composition may range from about 99:1 to about:90, and preferably from about 98:2 to about 70:30.

Conventional colorants may be used in conventional quantities in thecompositions of this invention. Suitable pigments include carbon black,zinc oxide, titanium dioxide, phthalocyanine blue, phthalocyanine green,benzidine yellow, naphthol yellow lake, cadmium orange, cadmium yellow,chrome yellow, Prussian blue, bronze blue, chrome green, peacock bluelake, milori blue, ultra'marine blue, red lake C, para red toluidinered, sodium lithol red, barium lithol red, lithol rubine, molybdatedscarlet chrome, ferric oxide, aluminum hydrate, and the like. Thevehicle may be used in an amount ranging from about 20 to 99.9 percentof the weight of the total composition and the amount of colorant mayrange from about 0.1 to 80 percent of the weight of the totalcomposition.

Other commonly known modifiers may be incorporated into the formulationsusing the compositions of the present invention. These includeplasticizers; wetting agents for the colorant,"such asdichloromethylstearate and other chlorinated fatty esters; levelingagents, such as lanoline, parafiin waxes, and natural waxes; and thelike. Such modifiers are generally used in amounts ranging up to 3, andpreferably about 1 percent, based on the total weight of theformulation.

The formulations using the compositions of this invention may beprepared in any convenient manner, such as, for example, in a three-rollmill, a sand mill, a ball mill, a colloid mill, or the like, inaccordance with known dispersion techniques.

Variables which determine the rate at which a radiation-curablecomposition will dry include the nature of the substrate, the specificingredients in the composition, the concentration of of thephotoinitiator, the thickness of the material, the nature and intensityof the radiation source and its distance from the material, the presenceor absence of oxygen, and the temperature of the surrounding atmosphere.Irradiation of the compositions may be accomplished by any one or acombination of a variety of methods. The composition may be exposed, forexample, to actinic light from any source and of any type as long as itfurnishes an effective amount of ultraviolet radiation, since thecompositions of this invention activatable by actinic light generallyexhibit their maximum sensitivity in the range of about 1800 A. to 4000.A. and preferably about 2000 A. to 3500 A.; electron beams; gammaradiation emitters; and the like; and combinations of these. Suitablesources include, but are not limited to, carbon arcs, mercury-vaporarcs, Van der Graaff accelerators, Resonant transformers, Betatrons,linear accelerators, and so forth.

The time of irradiation must be sufiicient to give the effective dosage.Irradiation may be carried out at any convenient temperature, and mostsuitably is carried out at room temperature for practical reasons.Distances of the radiation source from the work may range from about to10 inches, and preferably from about /8 to 3 inches.

Inks, coating compositions, adhesives, and the like made from thecompositions of this invention possess many advantages over theconventional solvent-type inks, coatings, adhesives, etc, In the firstplace, the use of volatile solvents'and the attendant hazards and odorare eliminated. The inks, coatings, and adhesives have excellentadhesion to the substrate after exposure to radiation. They have goodgloss and rub-resistance and withstand temperatures as high as C. and aslow as -20 C. The printed or coated sheets can be worked and turnedimmediately after exposure to the energy source.

In order to determine the lithographic efiiciency of the compositions,the inks are subjected to litho break tests which involve running themon a Thwing-Albert litho break tester together with fountain solutionand evaluating the resultant product by conventional techniques. Theamount of water take-up is also determined by weighing the ink remainingon the rollers after the break test, both before and after being driedin an oven. In addition, the inks are run on a process to evaluate theiractual lithographic efiiciency.

While there are disclosed below but a limited number of embodiments ofthe invention herein presented it is possible to produce still otherembodiments without departing from the inventive concept hereindisclosed. It is desired, therefore, that only such limitations beimposed on the appended claims as are stated therein. Unless otherwisespecified, all parts are given by weight.

EXMPLE 1 (A) In a 5-liter three-necked flask connected with a stirrer, athermometer, and a condenser were placed 1420 ml. of dried benzene, 409grams (3 moles) of pentaerythritol, 3 grams of cuprous oxide (aspolymerization inhibitor), 46 grams of concentrated sulfuric acid (ascatalyst), and 1296 grams (18 moles) of glacial acrylic acid with 1percent of p-methoxyphcnol (as inhibitor).

The mixture was heated at about 88 C. until 62.3 grams (3.46 moles) ofwater of esterification per mole of pentaerythritol was removed.

After cooling, the mixture was washed with 700 ml. of 20 percent NaClsolution, twice with 350 ml. of 24 percent KHCO solution, and finallywith 350 ml. of 20 percent NaCl solution. The benzene solution wasfiltered, 0.8 gram of p-methoxyphenol added, and the remaining solventremoved in vacuum using copper wire as an inhibitor.

The yield was 316 grams per mole of the pentaerythritol employed of apale yellow liquid which, upon standing, solidified to a semi-solidmelting at 4849 C. and having a viscosity of 875 cps. Analysis showed1.5 percent volatiles and an equivalent weight of 95.0, based on thesaponification value.

The product was accordingly assigned the empirical formula indicatingthat it was a mixture of pentaerythritol triacrylate and pentaerythritoltetraacrylate in the ratio of 0.54:0.46 mole, havinga hydroxylequivalent of 607.

(B) 607 grams of the product of part (A) was placed in a dry,three-necked flask equipped with an agitator, a thermometer, a droppingfunnel, and a gas inlet and outlet tube. At room temperature whileagitating the charge and passing a small stream of dry air through theflask above the surface of the liquid, 72.6 grams (0.6 mole) of phenylisocyanate was added slowly through the dropping funnel. Aftercompletion of the addition (about 1 hour), the reaction mass was allowedto stand for three hours and then discharged.

The product was a viscous, slightly yellow liquid having a viscosity of2680 cps., as measured with a Brookfield Viscosimeter (#4 spindle at 60r.p.m.). Infrared analysis (4.95 ,uscan) indicated the absence of theisocyanate peak and hence complete reaction. The product was a mixtureof unmodified pentaerythritol triacrylate, unmodified pentaerythritoltetraacrylate, and pentaerythritol triacrylate-monoph'enyl carbamatehaving a hydroxyl number of 31.3.

7 (C) An ink was prepared by grinding the following ingredients on athree-roll mill:

Percent 70/30 mixture of the product of part (B)/hexachlorobenzene 85Benzidine yellow 15 The ink was run on a Miehle press to print coatedpaper. The printed paper was exposed at a distance of 1% inches fromthree 20-inch 2l00-watt Hanovia ultraviolet lamps. The ink dried in 0.8second and had excellent gloss and water-resistance.

EXAMPLE 2 (A) 607 parts of pentaerythritol-3,4,6-acrylate, prepared bythe process of part (A) of Example 1 and having a refractive index of n=1.4850, was charged into a dry, three-necked flask equipped with anagitator, a thermometer, a dropping funnel, and gas inlet and outlettube. While agitating at room temperature and passing a small stream ofdry air through the flask above the surface of the liquid, 26 parts oftolylene-Z,4-diisocyanate (0.15 mole) was slowly over a period of 30minutes introduced through the dropping funnel. After the completion ofthe addition, the reaction mass was allowed to stand for several hoursand then discharged.

The product was a viscous, slightly yellow liquid having a viscosity of2460 cps., as measured at 25 C. with a Brookfield Viscosimeter (#4spindle at 60 r.p.m.). h1- frared analysis indicated the absence of theisocyanate peak and hence complete reaction after 20-hours reactiontime. The material was a physical mixture of unchanged pentaerythritoltriacrylate, unreacted pentaerythritol tetraacrylate, and the reactionproduct of pentaerythritol triacrylate with tolylene-2,4-diisocyanate,that is the compound of the formula o l l omQ-Hrtd oornowmo d (mom OOCI-hC (C11 0?!) OI-LCHDB having a hydroxyl number of 60.7.

(B) The procedure of part (C) of Example 1 was repeated using a 70/ 30mixture of the product of part (A) and a chlorinated paraffin (sold byNeville Chemical Co. as Unichlor-70B). The results were comparable.

EXAMPLE 3 EXAMPLE 4 (A) 456 parts of dry benzene and 261 parts of2,4-tolylene diisocyanate were charged into a dry, three-necked flask.While cooling and maintaining the temperature at 25-30 C., there wasadded over a period of 15 minutes 195 parts of dry 2-ethyl hexanolcontaining 1 part of dibutyl tin acetate. The liquid reaction mass wasstirred at room temperature for several hours and then allowed to standovernight.

The reaction mass, an almost colorless non-viscous liquid, was freedfrom the benzene solvent under vacuum, first at 125 torr and up to 70 C.and then at torr and 80 C. The vacuum was released with nitrogen, andthe reaction mass discharged. The yield was 459 parts of liquid4,N,2-isocyanato-toluyl-p-ethyl hexyl carbamate having the formula NCO(B) 607 parts of pentaerythritol-3.46-acrylate, prepared by the processof part (A) of Example 1, and 0.5 part of dibutyl tin acetate werecharged into a dry, threenecked flask equipped with an agitator, athermometer, a dropping funnel, and a gas inlet and outlet tube. Whileagitating at 45 C. and passing a small stream of dry air through theflask above the surface of the liquid, 98.8 parts of4,N,2-isocyanato-toluyl-fi-ethyl hexyl carbamate prepared as in part (A)was charged at once through the dropping funnel. The liquid reactionmass was stirred at 45 C. for several hours, allowed to stand overnight,and then discharged.

The reaction product was a viscous, slightly yellow liquid having aviscosity of 4560 cps., as measured at 25 C. with a BrookfieldViscosimeter (#4 spindle at 60 r.p.m.). Infrared analysis of the productindicated the absence of the isocyanate absorption peak and, therefore,complete reaction at 20-hour reaction time. The material was a physicalmixture of unchanged pentaerythritol triacrylate, unreactedpentaerythritol tetraacrylate, and the reaction product ofpentaerythritol triacrylate with 4,N,2-isocyanato-toluyl-fl-ethyl hexylcarbamate, that is, the compound having the formula (C) The product ofpart (B) was formulated into an ink and run as in part (C) of Example 1.The results were comparable.

EXAMPLE 5 The procedures of parts (B) and (C) of Example 4 were repeatedexcept that the carbamate was a /20 mixture of4,N,2-isocyanato-toluyl-B-ethyl hexyl carbamate and6,N,2-isocyanato-toluyl-fl-ethyl hexyl carbamate. The results werecomparable, except for the added presence of the reaction product ofpentaerythritol triacrylate with the 6,N,2-isocyanato-toluyl-B-ethylhexyl carbamate isomer.

EXAMPLE 6 A composition consisting of 70 parts of the product of part(B) of Example 1, 30 parts of benzophenone, and 0.1 part of dimethylpolysiloxane (to promote wetting) was applied in thicknesses rangingfrom 0.25 to 3.0 pounds per ream to each of the following substrates:book cover stock, clay-coated board, offset stock, can labels, andpolyethylene board. The printed substrates were cured by exposure at therate of 50 feet per minute at a distance of 1 inch from a 1200-wattHanovia ultraviolet energy source.

The resulting products were superior in gloss properties, adhesion, andabrasion resistance to comparable products prepared in the same mannerexcept with unmodified pentaerythritol triacrylate.

EXAMPLE 7 The composition of Example 6 was applied by a letterpressmethod at film weights ranging from 0.5 to 3.0 pounds per ream to eachof these substrates: Sarancoated cellophane, polyethylenesurface-treated with corana discharge, polyvinylidene dichloride-coatedpolypropylene, and Mylar. Laminations were made at F.

9 and 50 pounds/inch pressure between cellophane and cellophane,cellophane and polypropylene, polypropylene and Mylar, and then cured byexposing them at the rate of 50 feet per minute at a distance of 1 inchfrom a 1200 watt Hanovia ultraviolet lamp. The laminations weresuccessful as evidenced by tear seals having bond strengths of at least300 grams per inch.

EXAMPLE 8 (A) A composition consisting of 70 parts of the productof part(B) of Example 1 and 30 parts of benzoin methyl ether cured to atack-free dry film in 0.7-0.8 second when exposed at a distance of 1%inches to actinic radiation from a 2100-watt Hanovia ultraviolet lamp.

"(3) Under the same conditions, a composition consisting of 70 parts ofunmodified pentaerythritol-3.46- acrylate and 30 parts of benzoin methylether cured to a tack-free film in 1.0 to 1.2 seconds.

EXAMPLE 9 (A) The procedure of part (B) of Example 1 was repeated exceptthat the monomer was trimethylolpropane- 2.53-acrylate instead ofpentaerythritol-3.46-acrylate. The product had a hydroxyl number of 33.

(B) 'A mixture of 70 parts of the product of part (A) and 30 parts ofbenzoin ethyl ether dried to a tack-free film in less than 1.5 secondswhen exposed at a distance of 1% inches to an actinic energy source of2100 watts.

(C) Mixtures of 70 parts of each of the reaction prodnets of thefollowing trimethylolpropane acrylates and an isocyanate and 30 parts ofa mixture of biphenyls and triphenyls containing 65 percent of chlorinewere exposed on glass substrates at a distance of 1% inches from aIOO-Watt/inch ultraviolet lamp. The cure speeds of the films are givenbelow:

The procedures of parts (A) and (B) of Example 10 ,were repeated exceptthat each of the following monomeric materials was used instead oftrimethylolpropane- 2.53-acrylate: trimethylolethane 2.53 acrylate,trimethylolpropane 2.06 methacrylate, pentaerylthritol trimethacrylate,pentaerythritol diitaconate, and a mixture of dimers and trimers ofpentaerythritol triacrylate. The results were comparable.

EXAMPLE 12 (A) The procedure of part (B) of Example 1 was repeated withpentaerythritol acrylates having ester ranks 10 other than 3.46. Byester rank is meant the degree of esterification, that is, the averagenumber of ester groups per molecule. The viscosities of the resultingcarbamates are tabulated below.

(B) The products of part (A) were cured by exposing them on glasssubstrates at a distance of 1% inches from a 2100-watt/inch ultravioletlamp. The cure speeds are tabulated below.

TABLE II Cure speed secon Ester rank of pentaerythritol Viscosity, cps.

' EXAMPLE 13 (A) The procedure of part (B) of Example 1 was repeatedexcept that each of the following isocyanates was used instead of phenylisocyanate. The viscosity of each carbamate product is tabulated below.

(B) The products of part (A) were cured by exposing them on glasssubstrates at a distance of 1% inches from a 2l00-watt/inch ultravioletlamp. The cure speeds are tabulated below.

TABLE III Cure N (30/ OH Viscosity, speed, Isoeyanate ra 'o cps. seconds0. 2 2, 000 1. 1 0. 4 4, 610 0.7 0. 6 12, 600 0.5 o-Toly1 isocyanate 0.6 3, 580 0. 7 p-Chlorophenyl isocyanate- 0. 6 5, 730 0. 8 Cyclohexylisocyanate.-- 0. 6* 3, 100 0. 8 Allyl isocyanate 0. 6 1, 300 0. 97Methyl isocyanate 0. 56 1, 700 0. 6

" Plus 0.2% stannous octoate as catalyst.

EXAMPLE 14 The procedure of part (C) of Example 1 was repeated exceptthat each of the following proportions of ester to photoinitiator wasused'instead of 70/30: 99/1, 90/10, /20, 50/50, 20/80, and 10/90. Theresults were comparable.

EXAMPLE 15 The procedure of part (C) of Example 1 was repeated with eachof the following colorants instead of benzidine yellow: lithol rubinered, phthalocyanine blue, carbon black, milori blue, and phthalocyaninegreen. The results were comparable.

EXAMPLE 16 To demonstrate the relationship between hydrophilicity ofmonomeric esters and their suitability as vehicles for lithographicinks, the following runs (shown in Table IV) were made onpentaerythritol acrylates ranging in ester rank from 2.5 to 4, bothunmodified and modified with varying amounts of phenyl isocyanate.Hydrophilicity was measured. by a test which determines the watertolerance of a material by titrating a solution of the material in amixture of ethanol and acetone with water to a cloud end point, i.e., asolution opacity through which 3-point type printed matter becomesillegible.

The results are reported as the volume of water (ml.)

'used. to titrate the sample. A Water tolerance 'value of TABLE IVPentaerythritol acrylates Modified pentaerythzitol acrylates Water Watertolerance, Phenyl tolerance, Press Ester rank ml. isocyanate ml.characteristic 2.5.- 24.2 2.5 17. 12. 9 Some tinting. 2.5 22. 5 10. 7Excellent. 2.5 38. 0 7. 1 Stripping. 2.7.- 22.1 0 2.7.. 17.5 12. 2 S1.tinting. 2.7.- 19. 5 10. 9 Excellent. 2.7.. 33. 0 6. 1 Stripping. 2.9.21. 2 0 2.9 17.5 11. 4 Good. 2.9 18.0 11.0 Excellent. 2.9 25.0 6.4Stripping. 3.1- 0 3.1.. 10.0 11. 9 S1. tinting. 3.1 14. 0 10. 5Excellent. 3.1 17. 5 8. 6 Stripping. 3.3 0 3.3 10.0 12.3 S1. tinting.3.3 13.0 11.2 Excellent. 3.3 17 5 8. 3 Stripping. 3.5 0 3.5 11. 0Excellent. 3.5 15. 0 S1. stripping. 3.7-.-" 14.0 0 3.7 9. 0 Excellent.3.9 13.5 0 3.9 2. 8 12.3 S1. tinting. 4.0 1 13.5 0

1 Recrystallized.

=not acceptable as lithographic printing ink vehiele due to severescumming, tinting, or blanket contamination; tinting=emulsified inkappears in non-print areas; strippmg=ink does not pick up sufficient waer.

These data show that compounds having a water tolerance between about8.8 and 12.3 are good lithographic printing ink vehicles. These suitablewater tolerance values are obtained when pentaerythritol acrylates aremodified with phenyl isocyanate in varying amounts, as shown in Table V.

TABLE V Phcnyl isocyanate percent, based on weight of the acrylatcPentaerythrltol aerylates, ester rank EXAMPLE 17 To show the reductionin toxicity eifected by the isocyanate-modification of monomeric esters,both the acute oral toxicity and the dermal irritation ofpentaerythritol- 3.3-acrylate and pentaerythritol-3.3-acrylate modifiedwith 11 percent of phenyl isocyanate with and without a photoinitiatorwere determined by Food & Drug Research Laboratories, Inc., test methodsand compared with the acilite oral toxicity of aspirin. The results aretabulated be ow:

It can be seen from the above data that the isocyanatemodifiedpentaerythritol-3.3-acrylate, both with (2) and without (1) aphotoinitiator, exhibits less acute oral toxicity than either unmodifiedpentaerythritol-3.3-acrylate (3) or aspirin (4). In addition, the dermalirritation caused by the modified ester, both with and without aphotoinitiator, is substantially less than the dermal irritation causedby the unmodified ester.

EXAMPLE 18 To demonstrate the importance of using a polyethylenicallyunsaturated ester for the end uses for which the compositions of thisinvention are best suited, the procedures of parts (B) and (C) ofExample 1 were repeated with each of the following monoethylenicallyunsaturated monomeric esters instead of pentaerythritol-3.46-acrylate:hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxyhexylacrylate. In each of these cases where the starting ester wasmonoethylenically unsaturated the isocyanate-modified product was notacceptable because the speed of curing was too slow, the solutionviscosity was too high, and the surface properties were poor.

EXAMPLE 19 In order to show the need for the presence of unreactedhydroxy groups in the product, the procedures of parts (B) and (C) ofExample 1 were repeated except that instead of thepentaerythritol-3.46-acrylate, the starting monomeric ester Wastrimethylolpropane 2.5- methacrylate. Thetrimethylolpropane-Z.S-methacrylate was reacted with suflicient phenylisocyanate to convert all of the hydroxyl groups to carbamate groups.The isocyanatemodified product was not acceptable as a lithographic inkvehicle because of stripping.

EXAMPLE 20 The procedures of Examples 1-l5 were repeated except thatinstead of being exposed to ultraviolet light the samples were passed ona conveyor belt beneath the beam of a Dynacote 300,000-volt linearelectron accelerator at a speed and beam current so regulated as toproduce a dose rate of 0.5 megarad.

These systems produced resinous materials of varying degrees of hardnessin films from 0.5 to 20 mils thick having tacky surfaces.

EXAMPLE 21 The procedures of Examples 1-15 were repeated except thatinstead of being exposed to ultraviolet light the samples were exposedto a combination of ultraviolet light and and electron beam radiation ina variety of arrangements: ultraviolet light, then electron beam;electron beam; then ultraviolet light; ultraviolet light before andafter electron beam; and electron beam before and after ultravioletradiation. The results were comparable.

What is claimed is:

1. A radiation-curable composition which consists essentially of (1)about 10 to 99 weight percent of at least one product of the reaction of(a) a polyfunctional polyethylenically unsaturated monomeric esterhaving free hydroxyl groups and formed by the reaction of anethylenically unsaturated acid and a polyhydric alcohol with (b) anorganic isocyanate, the isocyanate-modified ester product (1) having ahydroxyl number of about 15 to 70, and (2) about 1 to weight percent ofat least one photoinitiator.

2. The composition of claim 1 wherein the hydroxyl number of theisocyanate-modified ester product is about 25 to 60.

3. The composition of claim 1 wherein the ratio of theisocyanate-modified ester product to the photoinitiator is about 70 to98:2 to 30.

4. The composition of claim 1 wherein the ester (21) is a diorpolyacrylate, a dior polymethacrylate, or a dior polyitaconate.

5. The composition of claim 1 wherein the polyhydric alcohol ispentaerythritol.

6. The composition of claim 1 wherein the polyhydric alcohol istrimethylolpropane.

7. The composition of claim 1 wherein the polyhydric alcohol istrimethylolethane.

8. The composition of claim 1 wherein the ester (a) 10 is apentaerythritol acrylate having an average of about 2.5 to 3.0 estergroups per molecule.

9. The composition of claim 1 wherein the isocyanate is phenylisocyanate.

10. The composition of claim 1 wherein the isocyanate 15 is tolylenediisocyanate.

14 References Cited UNITED STATES PATENTS 3,425,988 2/ 1969 Gorman et al260-47 3,297,745 1/1967 Fekete et a1. 260--47 3,495,987 2/1970 Moore96ll5 3,509,234 4/1970 Burlant et a1. 204159.15 3,664,861 5/ 1972Okamura et a1. 204-159z19 JOHN C. BLEUTGE, Primary Examiner R. B. TURER,Assistant Examiner US. Cl. X.R.

117-132 R, 138.8 R, 138.8 B, 138.8 E, 148, 155 UA, 152 R, 161 R, 116 UT;161-416, 249; 204-45915, 159.22, 159.24; 260-18 TN, 28.5 R, 31.2 N, 41R, 41 B, 41 C 3,759,809 September 18, 1973 Patent No.

Dated Inventor(s) Daniel J. Car-lick et 211.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 6, line 16, change "process to ----f "press line 25, change"EXMPLE" to EXAMPLE --q n Column 7, line 14, change "3,4,6" to 3, 46

Column 8, line 38, change y l to I r O--CH 0-011 Column 11, line 72,insert a superscript before "7.4"

Co1umnl2, line 54, delete the first "and"; line 56, after "beam" changeto Claim 8, line 3, change "3.0" 1:0 3.9

Signed and sealed this 18th day of December 1973.

(S Attest:

EDWARD M.FLETCHER,J R'. a RENE D. TEGTMEYER A ttesting Officer ActingCommissioner of Patents

